Process and apparatus for centrifugal separation



Apr. l?, 1923.

C. A. PORTER ET AL PROCESS AND APPARATUS FOR CENTRIFUGAL SEPARATIONFiled Nov. 19. 1921 ATTO RNEY WITNESS: y

Patented Apr. 17, 1923.

CLOVIS A. PORTER AND OSWALDO. BREWSTR, ONE-HALF TO PATRICK SULLIVAN ANDG. R.

F CASPER, WYOMING, ASSIGNORS OF HAGENS, BOTH 0F CASPER, WYOMING.

PROCESS AND APPARATUS FOR CENTRIFUGAL SEPARATION.

.application iled November T 0 all whom t may concern Be it known thatwe, CLovrs A. PORTERv and OSWALD C. BREWSTER, citizens of United States,residing at Casper, Wyoming, have invented new and useful Improvementsin Processes and Apparatus for Centrifugal Separation, of which thefollowing is a specilication.

The object of the present invention is the production of a process andapparatus for treatin lubricating oils containing waxy materia s,particularly uncrystallized paraflin wax or petrolatum and similarmaterials, for the separation from such oils, of

such waxy materials.

Processes have already been proposed in which the oil is first dilutedwith a suit.- able liquid which at a relatively high temperature forms asolvent for both the oil and waxy material, but which at a lowtemperature does not form a good solvent for the waxy material, but doesform a good solvent for the oil. An example of such a liquid is ordinarynaphtha produced in 'the distillation of petroleum oils, as one of thelighter fractions. y

The apparatus of the present invention is shown, more or lessdiagrammatically, in the annexed drawing, in which 10 represents asuitable frame and 11 represents a bowl of a centrifugal liquidseparator. This bowl is ordinarily made of considerable length, only thetop portion and the bottom portion being shown in the drawing. 12indicates a pipe through which the mixed and refrigerated liquid isintroduced. this liquid for example being a mixture of the heavylubricating oil to be treated, and a solvent. such as gasolene ornaphtha, already refrigerated to the desired low temperature. There isalready provided in the centrifugal -machine, a layer 13 of a suitableliquid which is not miscible with the oil or solvent, and which will notfreeze at the lowest temperatures attained by it, as employed in theprocess. A solution of calcium chlorid may be mentioned, by way ofexample. The liquid is fed in through the connection 14 into the space15, from which it passes into the conduit 16 and into the bottom of thecentrifugal rotary bowl. One or more fins or blades 17 are positioned inthe bowl, ad-` jacent to the inlet opening 16, for giving the liquid arotary motion, corresponding with that of the bowl, as soon as saidliquid 19, 1921. Serial No. 516,495.

enters the said bowl. The said blades are rigidly attached to the sidesof the bowl or to the cap 18 forming the bottom of the bowl.

In the bowl 11 the-liquid accordingly will rotate with the Same speed asthe bowl itself, whereby it readily becomes stratified, forming layerswhich are more or less distinct from each other. The line 20 indicatesthe inner wall of the layer of carrier liquid in the bowl. Line 21indicates the inner wall of the layer of waxy material, which isseparated by the centrifugal force, from the solution of oil in solvent.Line 22 represents the inner wall of the layer of oil in solvent. 23represents an annular double dam plate; the inner edge of this plate at24 forms the wall over which the light liquid, namely, solution of oilin solvent, from which the wax has been removed, passes into the chamber25. The outer edge of the plate 23 at 26 forms the dam under which theseparated waxy material passes from the main bowl into the space 27hereinafter referred to as auxiliary compartment. It is to be understoodthat the plate 23 can be made in one piece, as illustrated, or ifdesired, can be made in two pieces which either fit against each otheror overlap. The plate 23 is secured by suitable screws or rivets 29 tothe flange 30 carried at the lower end of pipe 31, this pipe forming theshaft by means of which` the bowl is rotated. The liquid entering thecompartment 25 Hows out through the radial pipes 32, into the spaceabove the cone 33 and below the cone 34. From the said space orcompartment the wax-free solution of clear oil is run olf in anysuitable manner to a storage tank or to a still in which the naphtha isseparated from the wax-free oil.

It is understood that the liquid 13 is previously introduced into thebowl of the separator in any suitable manner, before the introduction ofoil begins. This liquid need not be refrigerated at the time it isintroduced, but the mixture of oil in solvent introduced through pipe 12is already at a su'liciently low temperature to maintain the liquid `13cold. It is not. necessary torefrigerate the liquid during its passagethrough the centrifugal machine, as inordinarily running, bysulliciently cooling the liquid before the same enters through the pipe12, the liquid will not warm up in its passage through the bowl 11sufficiently to redissolve any substantial portion of the precipitatedwax.

A heated carrier liquid, preferably of the same composition as theliquid 13 enters through the pipe 40 at the top of the apparatus. Thisliquid travels downwardly through the pipe 31 and passes outwardlythrough the radial holes 42 which are placed near the lower end of thepipe 31, and preferably just above the plate 43 which forms a, completeclosure in the lower part of the pipe 31, just above the outlets 32,through which the wax-free solution of oil leaves the bowl. The passages42 being radial, the liquid passing out through these passages acquiresthe same circumferential velocity vas the bowl itself, which conditionis also assisted by the pipes 32 in the compartment 27. The liquidintroduced by 40 being hot, the wax in compartment 27 will readily bemelted and the centrifugal force will cause the separation of the wax ina molten state from said hot carrier liquid. In the upper end of thecompartment 27 is a second annular ring dam plate 46, the inner edge 47of which forms the overflow for the wax, this wax then passing outthrough the tubular passage 49 formed by the tube 50, said dry moltenwax passing out of the tube 50 at its top into the space between thecover 51 and the cone 52, from which space the dry molten wax is drawnoff in any suitable manner. The hot carrier liquid in the compartment 27passes under the outer edge 54 of the plate 46, into the space 55, fromwhich it passes through the tubular space 56 and over the dam 59, intothe space between the cone 52 and the cone 34, from which space the saidcarrier liquid is drawn off in any suitable manner. 'The plate 464 ispreferably, as indicated in the drawing, made integral with the tube 50,and this plate is fastened by means of the screws 60 to the ring 61,suitable spacing blocks 62 being placed at intervals around the upperside of the plate 46, in Athe compartment 55.

It is to be understood that a suitable motor will be attached to someportion of the length of the tubular shaft 70, for spinning thecentrifugal device at a high speed, sufficient for separating thesolidified wax from the solution of clear oil in solvent, which speedwill, of course, be amply sufficient for causing the separation of waxfrom carrier liquid in the compartment 27. It will be understood thatthe portion of the bowl 11, between the inlet 16 and the plate 23 willform the main centrifugal bowl, while the compartment 27, or spacebetween the plate 23 and plate 46 will form the auxiliary compartment.The speed of the centrifugal, the temperature of the liquid enteringthru pipe 12 and the speed of ow of this liquid, as well as thetemperature and speed of flow of the liquid entering thru pipe 40, willdepend upon the character of the oil being treated, and the degree towhich it is desired to remove the wax from the oil under treatment.Vithout limiting ourselves to details, we will state that in treatingordinary cylinder stock, the bowl may be rotated at a speed of 17,000revolutions per minute, the liquid entering thru pipe 12 being forexample 40% heavy oil and 60% naphtha, and being refrigerated to 0o F.,while the liquid entering thru pipe 40 may have a temperature of say 175to 200 F. Then by regulating the valve in pipe 12 and the valve in pipe40, the desired separation may be obtained.

The present invention comprises a substantial improvement over thecopending cases of O. C. Brewster, Serial No. 508,530 filed October 18,1921 and Serial No. 516,500 filed concurrently herewith, based upon thefact that in the present case the injection of the carrier liquid intothe upper compartment of the bowl is much more positive, therebyrendering control and adjustment of the degree of separation easier. Afurther advantage consists in that by centrifugally separating the waxfrom the carrier liquid, the separation is made much more complete andvery much quicker, and this is partlcularly true when certain kinds ofwaxes which are liable to form persistent emulsions are present,particularly when such carrier liquid contains substances which promoteemulsication of wax. I'n this connection, it may be noted that thecarrier liquid coming out at 59 is fed into a heater from which it againis introduced into the pipe 40, and by completely separating the carrierliquid from the wax, no wax is reintroduced with the circulating carrierliquid.

The plate shown at 17 preferably is continued from close to the inlet 16up to close to the plate 23. This device may preferably take the form ofa three wing device, namely, 3 wings or ns which radiate from the centerto the periphery of the bowl.

In a modified form, it is sometimes advisable to allow the wax andcarrier liquid to flow over the dam 59, after which the two may beseparated by gravity, after further heating. This, however, isordinarily not to be recommended. It will be understood that the cones33, 34 and 52, as well as the cover 51 are preferably stationary. Thesebeing spaced away a short distance from the rotating parts, and at theouter edges of the 3 compartments formed between the 4 elementsmentioned, suitable outlet s outs are provided, for separately drawing othe wax-free solution of oil, the carrier liquid and the molten wax.

1. A process of sepa-rating waxy material from oil, which comprisespassing a mixture of such oil with a solvent in such proportions as toproduce a liquid of low` viscosity, while refrigerated suiciently tocause solidiica-tion of a large part at least, of the waxy material,through a centrifugal separator while causing such mixture to float upona substantially non-progressing layer of aqueous fluid, withdrawing thesolution of clear oil -in solvent from the centrifugal, withdrawing theprecipitated waxy material to a separate compartment of the centrifugal,then adding to such waxy material, a warm, aqueous liquid in amountsufficient to melt said waxy material, subjecting the mixture of moltenwaxy material and water to centrifugal force and separately withdrawingthe separated wax and aqueous liquid.

2. A process which comprises passing a solution of viscous lubricatingoil containing waxes, in a solvent therefor, at a temperature at whichthe waxy materials are rendered largely insoluble, into and through acentrifugal rotor thereby, centrifugally separating the waxy materialsfrom the clear solution, drawing off the latter, mixing the separatedwaxy material with a warm liquid in which the same is insoluble to meltsaid wax material, centrifugally separating the resulting mixture andseparately drawing off the molten waxymaterial and the said liquid inwhich same is insoluble.

3. A centrifugal machine comprising a main bowl and an auxiliarycompartment rotating therewith, an inlet located axially of the mainbowl, an annular double dam plate in the opposite end of main bowl,separating said main compartment from said auxiliary bowl, the inneredge of they double dam plate communicating with an outlet for lightliquid, the space around the said double dam plate leading into saidauxiliary c'ompartment, a pipe leading centrally into said auxiliarycompartment, and having a radial hole into said latter compartment, anannular double dam plate in said auxiliary compartment, the inner edgeof said last named plate forming an outlet for light liquid from saidauxiliary compartment, the space around said last named plate leading toa separate outlet for heavy liquid for said auxiliary compartment.

4. In a centrifugal liquid separator comprising a main bowl and anauxiliary eompartment having the same axis of rotation, a main inlet atone end and an auxiliary inlet at the other end, said auxiliary inletformed of a conduit which is provided with a dam, and having a series ofholes in its sides in proximity to said dam, such holes being locatedwithin said auxiliary compartment.

In testimonywhereof we aix our signatures.

CLOVIS A. PORTER. OSWALD C. BREWSTER.

